ML17303A581

LER 87-002-01:on 870615,control Room Essential Filtration & Containment Purge Isolation Actuation Signals Received on Both Channels of Balance of Plant Esfas.Caused by Calibr of Static Transfer Switch.Switch recalibr.W/870918 Ltr

ML17303A581
Person / Time
Site:	Palo Verde
Issue date:	09/18/1987
From:	Bradish T, Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
192-00254-JGH-T, 192-254-JGH-T, LER-87-002, LER-87-2, NUDOCS 8709300055
Download: ML17303A581 (10)

Text

REGULA QY INFORNATION DISTR IBUTIO+YSTEN (RIDE)

ACCESSION NBR: 8709300055 DOC. DATE: 87/09/18 NOTARIZED: NO DOCKET ¹ FACIL: STN-50-530 Palo Verde Nuclear Stationi Unit 3> Arizona Pub 1 i AUTHOR AFFILIATlON 05000530'UTH.

NAME BRADISHI T. R. Arizona Nuclear Poeer Pro Ject (formerly Arizona Public Serv HAYNESI J. G. Arizona Nuclear Poujer Prospect (formerly Arizona Public Serv REC IP. NAME RECIPIENT AFFILIATION

SUBJECT:

LER 87-002-01: on 870615I control room essential filtration containment purge isolation actuation signals received on both channels of balance of plant ESFAS. Caused bg calibr of

'5000~~

static transfer smitch. Smitch recalibr. W/870918 ltr.

DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR 1 ENCL ( SIZE:

TITLE: 50. 73 Licensee Event Report (LER)I Incident Rpti etc.

NOTES: Standardized plant.

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 PD5 PD 1 1 LICITR*AE 1 1 DAVIS> M 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOEL'LER 2 2 AEOD/DOA 1 1 AEOD/DSP/NAS 1 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB 1 1

,DEDRO 1 1 NRR/DEST/ADS 1 0 NRR/DEST/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEST/ICSB 1 NRR/DEST/MEB 1 1 NRR/DEST/MTB 1 NRR/DEST/PSB 1 1 NRR/DEST/RSB 1 NRR/DEST/SGB 1 1 NRR/DLPG/HFB 1 NRR/DLPG/GAB 1 1 NRR/DOEA/EAB 1 1 NRR/DREP/R*B 1 1 NRR/DREP/RPB NRR/PM*S/ILRB RES DEPY GI 1

1 1

1 N

~L R/DRIS/SIB RES TELFORDI J 02 1

1 1

1 1

1' RES/DE/EIB 1 RGN5 FILE 01 1' EXTERNAL: EGGzG GROHI M 5 5 H ST LOBBY WARD 1 LPDR 1 1 NRC PDR 1 NSIC HARRIS, J. 1 1 NSIC MAYSI G 1 NOTES: 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 46 ENCL 45

Ol' 0

NRC Form 35$ US. NUCLEAR REOULATORY COMMISSION (903)

APPROVED OMS NO, 3150010(

LICENSEE EVENT REPORT ILER) EXPIRES: 5/31/SS FACILITY NAME (II DOCKET NUMSER (2) PA 0 5 0 0 0 5 3 1 OF 0 TITLE I ~ I En ineered Safet Feature Actuation EVENT DATE (5) LER NUMSER (5) REPORT DA'TE (7) OTHER FACILITIES INVOLVED (SI MONTH OAY YEAR YEAR I)/eT SEQUENTIAL REVISION OAY YEAR FACILITYNAMES DOCKET NVMSER(S)

NUMOER NUMOER MONTH N/A 0 5 0 0 0 0 6158 7 8 7 0 0 2 0 1 0 9 18 87 'N/A 0 5 0 0 0 THIS REPORT IS SUSMITTEO PURSUANT T 0 THE REQUIREMENTS OF 10 CF R (): /Corer onr or morr Of tnr foffowinf/ (11 OPER AT INC MODE ( ~ )

5 20A02(o) 20AOS(c) 50.734) (2)(iel 73.7(OI)

~OWER 20AOS( ~ l(1) (il 50.3$ (cl) I I 50.73(e) (2 I (el 73.71(c)

LEVEL p p p 20.40$ ( ~ )(1)(ill 50.3$ (c) (2( 50.734) (2)(YSI OTHER /Sprcify in Aettrect trrfow rodin Tref HRC Form 20AOS ( ~ I (1)(r(i) 50.73(e l(2) (il 50.73(e) (2) (eiii l(AI 3SSA/

20AOS(e I (1)(4) 50.734((2)(SI 50.7341(21<<E HEI 20.405(el(1) (e) 50.734) (2) Oii) 50.73(e) (2)(el LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE Thomas R. Bradish, Compliance Su ervisor 602 393 3531 COMPLETE. ONE LINE FOR EACH COMPONENT FAILURE DESCRISED IN THIS REPORT (13)

MANUFAC EPORTASLE MANUFAC.

CAUSE SY$ TEM COMPONENT TVRE,R TO NPRDS  :;~5Ii)Ir/pjg CAUSE SYSTEM COMPONENT TURER TO NPRDS .err'5)@'@@I Ig,(',

E F CNV E2'9 N

!4pgfk+~

,'~p); ~@jpg (Iei Ti@gkih'UPPLEMEN'TAL REPORT EXPECTED MONTH DAY YEAR FXPECTED SUSMISSION DATE (151 YES ilfyN, COmplrtr fXFECTED SUSM/$ $ /OH DATE/ NO AssTRAcT /Lim/t to lrOO epecee, fr.. epproeimrtrly fifteen einrlr enter typrwrHtrn /mrt/ (15)

This is a supplement to LER 3-87-002.

At approximately 0611 MST on June 15, 1987, Palo Verde Unit 3 was in Mode 5 (COLD SHUTDOWN) when Control Room Essential Filtration Actuation Signals (CREFAS) and Containment Purg'e Isolation Actuation Signals (CPIAS) were received on both channels of the Balance of Plant Engineered Safety Features Actuation System (BOP ESFAS). These BOP ESFAS actuations were annunciated in the control room on the main control board. All associated equ'ipment responded as designed.

Control room personnel secured all actuated equipment in accordance with approved procedures by 0657 MST on June 15, 1987. The duration of this event was approximately 46 minutes.

At approximately 0611 MST, the distribution panel D26 momentarily lost power and a "120VAC INV B AC/DC STATUS" trouble alarm was received for inverter "B". As designed, the static transfer switch automatically transferred from the "B" inverter to the 120 V AC voltage regulator. Immediately following the static transfer switch operation, both channels. of CREFAS and CPIAS were actuated on the BOP ESFAS system.

The root cause of this event was attributed to the static transfer switch calibration at an unnecessarily high value and a faulty DC to DC converter board. As a corrective action the static transfer switch was recalibrated and the DC to DC converter board replaced. A similar event was reported in LER 3-87-001.

/

V tt 8709300055 870918 PDR ADQCI('L 05000530 NRC Seem 304 S PDR

r.

V

NRC form 344A I943I US NUCLEAR REOULATORY COMMISSIDN LICENSEE EVENT REPORT {LER) TEXT CONTINUATION APPROVED OM4 NO. 3150-0104 EXPIRES: 4/31/44 FACILITY NAME III DOCKET NUMEER Ill LER NUM4ER 14) ~ AOE (31 YEAR ~~+or SEQUENT/AL Emof ASVISION NVM S/I NVM Palo Verde Unit 3 TEXT /// mo/9 sooco /f /NRIPSIE I/oo ~ Ar/IC Fo/m 34443/ IITI 0 5 0 0 o 530. 8 7 002 0 1, 02oF 0 This is a supplement to LER 3-87-002.

At approximately 0611 MST on June 15, 1987, Palo Verde Unit 3 was in Mode 5 (COLD SHUTDOWN)'ith Fuel Building Essential Filtration Actuation Signal (FBEFAS)(JE) in bypass and "B" train Essential Chiller (KM) tagged out for maintenance, when Control Room Essential Filtration Actuation Signals (CREFAS)(JE) and Containment Purge Isolation Actuation. Signals (CPIAS)(JE) were received on both channels of the Balance of Plant Engineered Safety Features Actuation System (BOP ESFAS)(JE). These BOP ESFAS actuations were annunciated in the control room on the main control board (MCBD). All associated equipment responded as designed. Control room personnel (utility-licensed) verified that all radiation parameters were in specification at the Radiation Monitoring System (RMS)(IL) display and secured all actuated equipment in accordance with approved procedures by 0657 MST on June 15, 1987. The duration of this event was approximately 46 minutes.

Prior to the event, Pre-Charge Circuitry Resistors (EF) in the "B" inverter (EF, INVT) had been installed under an approved work order. At 0525, "B" inverter was energized and placed in service powering distribution panel (EF) D26. All indications were normal at that time. At approximately 0611 MST, the "B" distribution panel (D26) momentarily lost power and "120VAC INV B AC/DC STATUS" trouble alarm (ALM) was received for inverter "B". As designed, the static transfer switch (ASU) automatically transferred to the 120 V AC voltage regulator (EF, RG). Inverter "B" normally supplies class lE 120 V AC power to the Engineered Safety Features (JE, ESF), Plant Protection System (JC, PPS) and various instruments and controls. Class 1E power is distributed to these systems via distribution panel D26. Inverter "B" is backed up by 120 V AC regulated power. Immediately following the static transfer switch operation, both channels of CREFAS and CPIAS were actuated on the BOP ESFAS system.

Previous inverter problems had been corrected and a design change implemented to prevent a loss of power to the class instrument AC busses (BU). The design change consisted of a static transfer switch designed to fast transfer the load to the AC voltage regulator upon an inverter malfunction. However, the static transfer switch did not actuate within the design specification. As a result, a momentary loss of power occurred to the D26 distribution panel. This caused Radiation Monitoring Units (IL) RU-30 (Channel "B" Control Room Ventilation Intake Monitor), and RU-38 (Channel "B" Power-Access Purge Area Monitor) to sense a loss of power and thus initiate the CREFAS and CPIAS actuations.

Troubleshooting conducted under an authorized work document revealed a faulty DC-DC converter (CNV) board. The DC to DC converter board converts 125 V DC power to isolated, low voltage power, which is needed to power the logic and inverter drive circuitry. The DC'o DC converter board power output was determined to be varying intermittently. A drop in the inverter logic 25 V DC 4AC ~ O/IM SOOA l9 SSI

NAC Poem S44A 19 dSI U.d. NUCLEAR AEOULATORY COMMISSION LICENSEE EVENT, REPORT {LER) TEXT CONTINUATION APPROVED OMd NO SI EO~IO4 EXPIRES: d/Slldd FACILITY NAME 111 OOCKET NUMEER QI LEA NUMEEA ldl PACE IS) 4 4 O V 4 Nn A L AEVI5ION YEAR gg NVM 4R NVM 4A TEXT NAuuP 4P444 A nosed, uw ~HRC Ann JAEALU(ITI 0 5 0 0 0 530 8 7 002 01 03 OF 0 3 power supply will cause the inverter to shutdown. Therefore, the spurious inverter malfunctions which have been previously identified are attributable to the faulty DC to DC converter board. As immediate corrective action, the DC to DC converter board was replaced. The converter board is manufactured by Elgar with the part number of 628-135-40.

Troubleshooting revealed that the setpoints on, the static transfer switch were calibrated at an unnecessarily high value. The setpoints were inadvertently calibrated at the high value during prev'ious troubleshooting. This caused the slow static transfer switch transfer time and resulted in the momentary loss of power to distribution panel D26 and subsequent ESFAS actuations.. As corrective action, the static transfer switch was recalibrated.

II Also, during troubleshooting a 300 amp fuse (FU) was found bl'own. The inverter control logic and driver boards were replaced and a replacement troubleshooting fuse (water) was installed until the conclusion of testing at which time a regular fuse will be installed.

Additionally, subsequent to this event, at 0627 an operator (licensed-utility) noticed "B" train Shutdown Cooling System isolation valve '(SlB-UV652)(JC) was closed. This valve is designed to fail "as is" on a loss of instrument power.

The valve was immediately opened and an Engineering Evaluation Request (EER) was written to determine why this valve closed.

.Since an actual emergency condition did not exist at the time of the event, there was no threat to the safe operation of the plant or the health and safety of the public. Had an emergency condition existed during the event, all safety equipment would have actuated as shown above.

There were no component, system, or safety train failures or malf'unctions, other than listed above, that contributed to this event. There were no unusual work conditions that contributed to this event. There were no operator actions which contributed to this event.

A similar event was reported in Unit 3 LER 3-87-001.

'aAC ~ 0AM 4444 19 dls

II Qi Arizona Nuclear Power Project P.O. BOX 52034 ~ PHOENIX. ARIZONA85072-2034 192-00254-JGH/TRB/ESP September 18, 1987 NRC Document Control Desk Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 3 Docket No. STN 50-530 Licensee Event Report 87-002-00 File: 87-020-404

Dear Sirs:

Attached please find Supplement No.l to Licensee Event Report (LER) No.

87-002-00 prepared and submitted pursuant to the requirements of 10 CFR 50.73(d).

We are herewith forwarding a copy of this report to the Regional Administrator of the Region V Office.

If you have any questions,'please contact T. R. Bradish, Compliance Supervisor at (602) 393-3531.

Very truly yours, J. G. Ha nes Vice President Nuclear Production JGH/ESP/cld Attachment cc: 0. M. DeMichele (all w/a)

E. E. Van Brunt, Jr.

J. B. Martin R. P. Zimmerman R. C. Sorenson E. A. Licitra A. C. Gehr INPO Records Center

4l i' ~W

'i I